Synthesis and Characterization of an Oxo-Centered Homotrimetallic Uranium(IV)-Cyclobutadienyl Dianion Complex
Synthesis and Characterization of an Oxo-Centered Homotrimetallic Uranium(IV)-Cyclobutadienyl Dianion Complex
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DOI：
10.1021/acs.organomet.0c00104
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发表时间：
2020-05-26
期刊：
影响因子：
2.8
通讯作者：
Liddle, Stephen T.
中科院分区：
文献类型：
--
作者：
Boronski, Josef T.;Doyle, Laurence R.;Liddle, Stephen T.
Reaction of [Li-2{C-4(SiMe3)(4)}(THF)(2)] (1) with [U(eta(5)-C5Me5)I-2(THF)] (2) produced the oxo-centered homotrimetallic uranium-pentamethylcyclopentadienyl complex [{U(eta(5)-C5Me5)(mu-I)(2)}(3){mu(3)-O}{Li(THF)(3)}(0)(.5)](2) [Li(THF)(4)] (3) as the only isolable product in a very low yield. In contrast, reaction of 2 with [Mg{C-4(SiMe3)(4)}(THF)(3)] (4) produced the oxo-centered homotrimetallic uranium(IV)-cyclobutadienyl complex [{U(C-4[SiMe3](4))(mu-I)(2)}(3){mu(3)-O}] [Mg(THF)(6)] (5). The solid state structure of 5 reveals average U-C and U-C-4 centroid distances of 2.574(7) and 2.355(7) angstrom, respectively, and displacements of the silicon atoms from the C-4 plane ranging from 0.478(13) to 0.6528(12) angstrom. Variable-temperature magnetic susceptibility measurements on powdered 5 confirm the exclusively uranium(IV) formulation with no evidence found for any uranium center dot center dot center dot uranium magnetic coupling. Quantum chemical calculations suggest polarized uranium-cyclobutadienyl bonding interactions but underscore the essentially exclusive pi-bonding nature of these linkages with no delta-bonding component. This pi-bonding also accounts for the displacements of the silyl groups from the C-4 plane, which maximizes U-C-4 orbital overlap. The compounds reported here have been variously characterized by single-crystal X-ray diffraction, ATR-IR spectroscopy, elemental analysis, SQUID magnetometry, and quantum chemical calculations.
